The end of the stars draws near. Three must become four to battle the darkness that lasts forever.

With a divided StarClan driving a treacherous rift between the four warrior Clans, the spirits of the Dark Forest are gaining strength. Ivypool’s role as a spy becomes more dangerous with each passing day, and Dovewing is haunted by nightmares about the mountains. An outsider appears in ThunderClan's midst, spreading discord and pushing the Clans further apart. As tensions mount and Clanmates turn against one another, the warrior cats will be forced to choose whose word they can trust—before it's too late.

The Clans are in turmoil. ShadowClan has turned its back on StarClan and pledged to follow the dark predictions of Sol, the strange cat who foretold the solar eclipse. But not all the cats have lost faith in their warrior ancestors...

Jaypaw is convinced that StarClan still holds an important place in the warrior code, and his search for answers leads him far back into the past, farther back than even StarClan can remember. Lionblaze, tortured by violent dreams and bloody visions, wishes he had never been prophesied to be one of the three, but to turn his back on his littermates would be the ultimate betrayal. And Hollyleaf is terrified that once the Clans lose their faith, the warrior code will fall apart. She's willing to fight tooth and nail to preserve it—whatever the cost.

And when murder stalks into the heart of ThunderClan, the cats realize that the darkest shadows don't always lie outside the territory.